Answer:
Mass = 2.355 g
Explanation:
Given data:
Mass of Kâ‚‚O needed = ?
Mass of KNO₃ produced = 5.00 g
Solution:
Chemical equation:
K₂O + Ca(NO₃)₂   →  CaO +  2KNO₃
Number of moles of KNO₃:
Number of moles = mass/molar mass
Number of moles = 5.00 g/ 101.1 g/mol
Number of moles = 0.05 mol
now we will compare the moles of KNO₃ and K₂O.
        KNO₃      :       K₂O
         2         :        1
         0.05      :      1/2×0.05 = 0.025 mol
Mass of potassium oxide needed in gram:
Mass =  number of moles × molar mass
Mass = 0.025 mol × 94.2 g/mol
Mass = 2.355 g
